1. Field of the Invention
The present invention relates to a process for the removal of naphthalene from a hydrocarbon stream carried out concurrently with fractional distillation within a distillation column reactor. More particularly the invention relates to a process wherein the naphthalene is converted to alkylnaphthalenes by transalkylation with alkylbenzenes. More particularly the invention relates to the conversion of naphthalene contained in aromatic solvents to alkylnaphthalenes by transalkylating the naphthalene in the aromatic solvent with alkylbenzenes contained within the solvent.
2. Related Information
Alkylbenzenes, naphthalene, and alkylnaphthalenes are produced as a by-product in olefin plants, fluid catalytic crackers, catalytic reformers and coal tar plants. Dialkylbenzenes have value as precursors of monomers for high performance polymers. Mixtures of alkylbenzenes and alkylnaphthalenes have found value as solvents.
The terms A150 and A200 have been applied in the industry to aromatic solvents produced by the separation of heavy boiling compounds from the effluent of gasoline catalytic reforming units and olefin plants. A150 and A200 are distilled in such a way as to afford flash points of 150° F. and 200° F., respectively. The heavier solvent contains significant amounts of naphthalene. Naphthalene has been identified as a carcinogen causing cancer, haemolytic anaemia (damage to red blood cells), and local respiratory tract irritation (nose and throat). It has therefore become desirable to remove naphthalene from these solvents.
U.S. Pat. Nos. 6,232,517 and 5,670,704 describe the chemistry for alkylating naphthalene in the presence of a solid catalyst to selectively yield 2,6 dimethylnaphthalene. U.S. Pat. Nos. 6,204,422, and 5,844,064 describe a chemistry wherein alkylnaphthalenes are produced by transalkylation over a catalyst. Finally U.S. Pat. No. 5,243,115 discloses a process whereby aromatic compounds are alkylated with an olefin, such as ethylene or propylene, in a distillation column reactor.